St John's wort, a herbal antidepressant, activates the steroid X receptor

in Journal of Endocrinology
Authors:
JM Wentworth
Search for other papers by JM Wentworth in
Current site
Google Scholar
PubMed
Close
,
M Agostini
Search for other papers by M Agostini in
Current site
Google Scholar
PubMed
Close
,
J Love
Search for other papers by J Love in
Current site
Google Scholar
PubMed
Close
,
JW Schwabe
Search for other papers by JW Schwabe in
Current site
Google Scholar
PubMed
Close
, and
VK Chatterjee
Search for other papers by VK Chatterjee in
Current site
Google Scholar
PubMed
Close
Free access

Sign up for journal news

St John's wort (SJW), an extract of the medicinal plant Hypericum perforatum, is widely used as a herbal antidepressant. Recently, this agent has been found to adversely affect the metabolism of various coadministered drugs. Steroid X receptor (SXR), an orphan nuclear receptor, induces hepatic cytochrome P450 gene expression in response to diverse endogenous steroids, xenobiotics and drugs. Here, we report that, when coexpressed with SXR, a reporter construct derived from the cytochrome P450 3A promoter is activated by St John's wort. A GAL4-SXR ligand binding domain (LBD) fusion mediates concentration-dependent transactivation by SJW, whereas a mutant GAL4-SXR fusion, containing substitutions in key residues in a transactivation domain, is inactive. SJW recruits steroid receptor coactivator-1 to SXR in a two-hybrid assay and competes with radiolabelled ligand in binding studies, suggesting it interacts directly with the receptor LBD. Of two constituents of SJW, we find that hyperforin, but not hypericin, mediates both transactivation and coactivator recruitment by SXR. Our observations suggest that SXR activation by St John's wort mediates its adverse interaction with drugs metabolised via the CYP 3A pathway. Future development of SJW derivatives lacking SXR activation, may enable its antidepressant and drug-metabolising properties to be dissociated.

 

  • Collapse
  • Expand